Audacity

Audacity is an audio editor of its own, so audio moves between Audacity and HARP as files.

Send Audio to HARP

1. Select the audio, and choose File > Export Audio (Ctrl+Shift+E), with Export Range set to Current Selection.
2. Drag the exported file onto an input track of a model in HARP, and select Process.

Bring the Result Back

Drag the output track from HARP into the project window of Audacity, which imports it as a new track, as File > Import > Audio does.